Spring assembly

Abstract

A supporting projection is formed on a resin base plate on which a seat winding portion of a coil spring is fitted. The supporting projection has such rigidity that a distal end portion does not deflect against a spring force applied radially inwards from the seat winding portion of the coil spring. On the other hand, an elastic deflectable area which deflects elastically by the spring force applied radially outwards from the seat winding portion of the coil spring is formed in an area which extends from a proximal end to the distal end portion of the supporting projection.

The invention claimed is: 
     
       1. A spring assembly, comprising:
 resin base plates; 
 a coil spring having seat winding portions fixed to the resin base plates; and 
 a supporting projection formed on each of the resin base plates so as to be fitted with the seat winding portion of the coil spring, the supporting projection including:
 a distal end portion having rigidity so as not to deflect against a spring force applied radially inwards from the seat winding portion of the coil spring; 
 a proximal end; and 
 an elastic deflectable area formed within an area which extends from the proximal end to the distal end portion so as to deflect elastically by the spring force applied radially inwards from the seat winding portion of the coil spring, 
 
 wherein, in the coil spring,
 the seat winding portion is contracted diametrically more than an intermediate winding portion, 
 a bore diameter of the seat winding portion is made smaller than an outside diameter of the distal end portion of the supporting projection, and 
 a bore diameter of the intermediate winding portion is made larger than the outside diameter of the distal end portion of the supporting projection, whereby the coil spring is fitted on the distal end portion of the supporting projection while being expanded elastically, 
 
 wherein a contracted portion is formed in the elastic deflectable area by fitting the seat winding portion of the coil spring on the supporting projection until reaching the elastic deflectable area, and when the contracted portion is formed, the distal end portion functions as a stopper to prevent dislocation of the coil spring from the supporting projection, and 
 wherein, when fitting the seat winding portion of the coil spring onto the supporting projection, the distal end portion of the supporting projection abuts with an inner circumferential surface of the seat winding portion of the coil spring through its entire inner circumference to thereby outwardly expand the seat winding portion of the coil spring. 
 
     
     
       2. The spring assembly according to  claim 1 ,
 wherein the supporting projection is hollowed at least in an area corresponding to the elastic deflectable area, and a circumferential wall of the same area is thinned, so as to allow the circumferential wall to deflect elastically by the spring force applied radially inwards from the seat winding portion of the coil spring. 
 
     
     
       3. The spring assembly according to  claim 1 ,
 wherein the supporting projection is hollowed at least in an area corresponding to the elastic deflectable area, and plural axial slits are formed in a circumferential wall of the same area, so as to allow the circumferential wall to deflect elastically by the spring force applied radially inwards from the seat winding portion of the coil spring. 
 
     
     
       4. The spring assembly according to  claim 1 , wherein the outside diameter of the distal end portion is equal to an outside diameter of the elastic deflectable area in a non-deflected state. 
     
     
       5. The spring assembly according to  claim 1 , wherein the supporting projection comprises a cylindrical shape having a constant outside diameter. 
     
     
       6. The spring assembly according to  claim 1 , wherein the elastic deflectable area and the distal end portion are sequentially disposed from the proximal end of the supporting projection to the distal end of the supporting projection. 
     
     
       7. The spring assembly according to  claim 1 , wherein a thickness of a circumferential wall of the elastic deflectable area is less than a thickness of the distal end portion. 
     
     
       8. The spring assembly according to  claim 1 , wherein the supporting projection is hollowed at least in an area corresponding to the elastic deflectable area, and a thickness of a circumferential wall of the same area is less than a thickness of the distal end portion. 
     
     
       9. The spring assembly according to  claim 1 , wherein the outside diameter of the distal end portion is substantially equal to an outside diameter of the elastic deflectable area. 
     
     
       10. A spring assembly, comprising:
 resin base plates; 
 a coil spring including seat winding portions fixed to the resin base plates; and 
 a supporting recess formed in each of the resin base plates so as to be fitted with the seat winding portion of the coil spring, a wall of the supporting recess including:
 an opening edge portion having rigidity so as not to deflect against a spring force applied radially outwards from the seat winding portion of the coil spring; 
 a bottom portion; and 
 an elastic deflectable area formed within an area of the wall of the supporting recess which extends from the bottom portion to the opening edge portion so as to deflect elastically by the spring force applied radially outwards from the seat winding portion of the coil spring, 
 
 wherein, in the coil spring,
 the seat winding portion is expanded diametrically more than an intermediate winding portion, 
 an outside diameter of the seat winding portion is made larger than a bore diameter of the supporting recess, and 
 an outside diameter of the intermediate winding portion is made smaller than the bore diameter of the supporting recess, whereby the coil spring is fitted in the opening edge portion of the supporting recess while being contracted elastically, and 
 
 wherein an expanded portion is formed on the elastic deflectable area by fitting the seat winding portion of the coil spring in the supporting recess until reaching the elastic deflectable area, and when the expanded portion is formed, the opening edge portion functions as a stopper to prevent dislocation of the coil spring from the supporting recess, and 
 wherein, in a state where the seat winding portion of the coil spring is not fitted in the supporting recess, a bore diameter of the opening edge portion is substantially equal to a bore diameter of the elastic deflectable area. 
 
     
     
       11. The spring assembly according to  claim 10 ,
 wherein at least an area of the supporting recess corresponding to the elastic deflectable area is configured of a thin cylindrical wall, so as to allow the cylindrical wall to deflect elastically by the spring force applied radially outwards from the seat winding portion of the coil spring. 
 
     
     
       12. The spring assembly according to  claim 10 ,
 wherein at least an area of the supporting recess corresponding to the elastic deflectable area is configured of a cylindrical wall, and plural axial slits are formed in the cylindrical wall, so as to allow the cylindrical wall to deflect elastically by the spring force applied radially outwards from the seat winding portion of the coil spring. 
 
     
     
       13. The spring assembly according to  claim 10 , wherein the bore diameter of the opening edge portion is equal to a bore diameter of the elastic deflectable area in a non-deflected state, and
 wherein the bore diameter of the opening edge portion increases as the opening edge portion extends away from the bottom portion. 
 
     
     
       14. The spring assembly according to  claim 10 , wherein the supporting recess comprises a cylindrical shape having a constant bore diameter. 
     
     
       15. The spring assembly according to  claim 10 , wherein the elastic deflectable area and the opening edge portion are sequentially disposed from the bottom portion of the supporting recess to a distal end of the supporting recess. 
     
     
       16. The spring assembly according to  claim 10 , wherein a thickness of a circumferential wall of the elastic deflectable area is less than a thickness of the opening edge portion. 
     
     
       17. The spring assembly according to  claim 10 ,
 wherein the wall of the supporting recess continuously extends from the resin base plate so that the opening edge portion is located within a range of a thickness of the resin base plate. 
 
     
     
       18. A spring assembly, comprising:
 resin base plates; 
 a coil spring having seat winding portions fixed to the resin base plates; and 
 a supporting projection formed on each of the resin base plates so as to be fitted with the seat winding portion of the coil spring, the supporting projection including:
 a distal end portion having rigidity so as not to deflect against a spring force applied radially inwards from the seat winding portion of the coil spring; 
 a proximal end; and 
 an elastic deflectable area which extends from the proximal end to the distal end portion so as to deflect elastically by the spring force applied radially inwards from the seat winding portion of the coil spring and has an outside diameter equal to an outside diameter of the distal end portion, the proximal end, the elastic deflectable area, and the distal end portion being sequentially disposed from the resin base plates; 
 a groove which hollows an interior of the supporting projection and extends from a rear surface side of the resin base plates to an upper edge of the elastic deflectable area which contacts the distal end portion, a center axis of the groove being equally distance to outer edges of the supporting projection in a direction perpendicular to the supporting projection, 
 
 wherein, in the coil spring,
 the seat winding portion is contracted diametrically more than an intermediate winding portion, 
 a bore diameter of the seat winding portion is made smaller than the outside diameter of the distal end portion of the supporting projection, and 
 a bore diameter of the intermediate winding portion is made larger than the outside diameter of the distal end portion of the supporting projection, whereby the coil spring is fitted on the distal end portion of the supporting projection while being expanded elastically.